(CNN) -- The U.S. Coast Guard called off a search Sunday afternoon for a sailor who went missing after an apparent collision during a boat race Saturday from Newport, California, to Ensenada, Mexico.

The collision left three other crew members from the 37-foot Aegean sailboat dead.

"It's always very difficult to suspend an active search," said Petty Officer Allyson Conroy, who extended her condolences to the families of the sailors involved.

The vessel, which was participating in the Lexus Newport to Ensenada Yacht Race, disappeared from the online race tracking system about 1:30 a.m. Saturday near the Coronado Islands, Mexico, race organizers said.

On Saturday afternoon, searchers found the three deceased crew members and debris from the Aegean.

Also found was the boat's wreckage, according to the race organizers, including the rear transom with the boat's name on it.

"An investigation was continuing, but it appeared the damage was not inflicted by an explosion but by a collision with a ship much larger than the 37-foot vessel," organizers said.

The U.S. Coast Guard could not confirm that a collision had occurred. An investigation is under way.

The fatalities were the first in the race's 65-year history, organizers said.

The incident follows a dangerous period for the ocean-racing world.

Earlier this month, five sailors died after their yacht ran aground off San Francisco. Their 38-foot sailboat was taking part in the Full Crew Farallon Race when it was hit by large waves that rolled it over, tossing several crew members overboard and running it aground.

In March, the Coast Guard rescued racers taking part in an around-the-world contest when a giant wave damaged their yacht off the coast of San Francisco. The Geraldton Western Australia was on the sixth leg of an eight-leg, 11-month race when it was struck March 31.